A Review on the Application of Biochar as a Self-Sensing and Self-Healing Additive in the Cementitious Composites

The biochar (BC) has seen usage in a diverse number of applications such as soil amendment, asphalt mix additive, waste water filtration and cementitious composites. These applications have also been continuously expanding through ongoing research efforts. In recent years, its use in cementitious composites has gained attention, particularly as a partial replacement for cement content to improve its strength and durability performance by enhancing its internal microstructure. More recently, biochar is being tested for certain novel implementations in the cementitious systems, particularly imparting self-sensing and self-repair properties to them. The research is being conducted to evaluate the potential of biochar in increasing the electrical conductivity of cementitious mixes, which could enable real-time structural health monitoring. Additionally, some studies have utilised biochar itself or as a carrier material for delivering self-healing bacteria and with other agents to repair any cracks formed during the lifetime of the cementitious material. While these innovative applications have shown promise, they are still in the initial phases of development. The present study aims to provide the state-of-the-art advancements in this field, which would offer insights into the underlying mechanisms and processes involved when BC is used for self-sensing and self-repair application in cementitious mixes, thereby guiding future research efforts.